The present invention relates to construction units, or blocks, and, more particularly to construction units having provision for directing condensation from the interior of the units to the exterior.
Most walls used in constructing buildings have vertical cavities in which condensation forms as a result of changes in temperature. This is true in walls constructed of conventional blocks of concrete or other materials which have hollow vertical cores extending through the blocks. In concrete block walls in which no provision is made for allowing the condensation to escape, the condensation builds up in pools at the bottom of the wall and gradually seeps through the concrete blocks at the bottom. This seepage through the material of the blocks results in stains on the exterior of the blocks caused by efflorescence. In efflorescence, the water seeping through the material of the blocks dissolves certain chemicals in the material and carries them to the surface of the block, where they cause stains.
A common method of allowing condensation to escape is to provide weep openings in a wall made of blocks by leaving out a portion of the mortar near the bottom of vertical joints between the blocks. Such an arrangement is not very effective because the openings in the mortar communicate with the joints between adjacent blocks, whereas most of the problem with condensation and other moisture in the blocks arises in the hollow cores, which are not in direct communication with the joints between adjacent blocks.
In an another known arrangement for allowing condensation to weep from the interior of a concrete block wall to the exterior, the bottom course of the wall is formed with a double course of blocks each having a depth approximately equal to one-half of the depth of the other courses of blocks. Flashing having a vertical section extending between upper and lower horizontal sections is positioned in the double course of blocks, with the upper horizontal section of the flashing extending over the top of the inner course of the double course, the vertical section extending between the inner and outer courses, and the lower horizontal section extending under the outer course. In addition, tubes or wicks are positioned above the lower horizontal section of the flashing and under the outer course to conduct the condensation from the interior of the wall to the exterior. This construction has the disadvantage that extra units must be assembled in the bottom course and the tubes or other devices must be inserted for proper drainage of the condensate. In actual construction conditions, workers often fail to install the tubes or other devices.
Although the present application specifically mentions condensation as the source of moisture in the wall, the moisture can be from other sources, such as the infiltration of rain into the wall through cracks, or leakage into the wall from other sources, or still other causes.